1. Field of the Invention
The present invention refers to a device for selectively dispensing limestone for regenerating ovens. The present invention further refers to a process for selectively loading limestone in a regenerating oven using such device.
2. Background Art
As known, parallel-flow regenerating ovens for manufacturing lime from limestone are composed of two vats, which are mutually interconnected through a connection channel.
Limestone is loaded in every vat and descends along the pre-heating area, in which regenerative heat exchange occurs in counter-current with fumes, passes the lances, which insert fuel and arrives to the baking/calcining area. From here, it reaches the lime cooling area.
The oven operation allows the alternate combustion in every vat with a combustion cycle which is 8 to 12 minutes long.
During every alternate combustion cycle, fuel is entered into the vat under combustion through the lances, and burns in the combustion air, which is blown into the vat, releasing heat, which is partly absorbed by the limestone calcining. Simultaneously, cooling air is entered at the base of every vat in order to cool the lime. The cooling air of the vat under combustion, together with combustion gases and carbon dioxide released from the limestone when calcining, pass through the transverse interconnected channel, reaching the other vat at a temperature up to 1050° C., in which they are mixed with cooling air at the base and rise, thereby heating the limestone which can be found in the heating area.
In traditional ovens, however, combustion gases rise along the vat through the limestone by travelling, due to their own physical nature, along the short trajectory, namely the one flanking the internal wall of each vat, making the heating of crosses limestone irregular.